After acquiring the Dwarven Crossbow Schematic in the second-to-last of the Ancient Technology missions, Sorine Jurard will begin to sell them. She may also teach the player how to forge them, if requested. May also be looted from Dawnguard NPCs.
After obtaining the schematics for the crossbow and asking Sorine Jurard how to make it, it may be forged with a smithing level of 30 and the Dwarven Smithing perk. It is only forgeable at the forge in Fort Dawnguard, using the following materials:
Must be placed in the 'Armory Storage' cabinet by the armory entrance for it to display.